1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2013-2015 Fujitsu Semiconductor Ltd.
4  * Copyright (C) 2015 Linaro Ltd.
5  * Based on ARM MHU driver by Jassi Brar <jaswinder.singh@linaro.org>
6  * Copyright (C) 2020 ARM Ltd.
7  */
8 
9 #include <linux/amba/bus.h>
10 #include <linux/device.h>
11 #include <linux/err.h>
12 #include <linux/interrupt.h>
13 #include <linux/io.h>
14 #include <linux/kernel.h>
15 #include <linux/mailbox_controller.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/of_device.h>
19 
20 #define INTR_STAT_OFS	0x0
21 #define INTR_SET_OFS	0x8
22 #define INTR_CLR_OFS	0x10
23 
24 #define MHU_LP_OFFSET	0x0
25 #define MHU_HP_OFFSET	0x20
26 #define MHU_SEC_OFFSET	0x200
27 #define TX_REG_OFFSET	0x100
28 
29 #define MHU_CHANS	3	/* Secure, Non-Secure High and Low Priority */
30 #define MHU_CHAN_MAX	20	/* Max channels to save on unused RAM */
31 #define MHU_NUM_DOORBELLS	32
32 
33 struct mhu_db_link {
34 	unsigned int irq;
35 	void __iomem *tx_reg;
36 	void __iomem *rx_reg;
37 };
38 
39 struct arm_mhu {
40 	void __iomem *base;
41 	struct mhu_db_link mlink[MHU_CHANS];
42 	struct mbox_controller mbox;
43 	struct device *dev;
44 };
45 
46 /**
47  * ARM MHU Mailbox allocated channel information
48  *
49  * @mhu: Pointer to parent mailbox device
50  * @pchan: Physical channel within which this doorbell resides in
51  * @doorbell: doorbell number pertaining to this channel
52  */
53 struct mhu_db_channel {
54 	struct arm_mhu *mhu;
55 	unsigned int pchan;
56 	unsigned int doorbell;
57 };
58 
59 static inline struct mbox_chan *
mhu_db_mbox_to_channel(struct mbox_controller * mbox,unsigned int pchan,unsigned int doorbell)60 mhu_db_mbox_to_channel(struct mbox_controller *mbox, unsigned int pchan,
61 		       unsigned int doorbell)
62 {
63 	int i;
64 	struct mhu_db_channel *chan_info;
65 
66 	for (i = 0; i < mbox->num_chans; i++) {
67 		chan_info = mbox->chans[i].con_priv;
68 		if (chan_info && chan_info->pchan == pchan &&
69 		    chan_info->doorbell == doorbell)
70 			return &mbox->chans[i];
71 	}
72 
73 	return NULL;
74 }
75 
mhu_db_mbox_clear_irq(struct mbox_chan * chan)76 static void mhu_db_mbox_clear_irq(struct mbox_chan *chan)
77 {
78 	struct mhu_db_channel *chan_info = chan->con_priv;
79 	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].rx_reg;
80 
81 	writel_relaxed(BIT(chan_info->doorbell), base + INTR_CLR_OFS);
82 }
83 
mhu_db_mbox_irq_to_pchan_num(struct arm_mhu * mhu,int irq)84 static unsigned int mhu_db_mbox_irq_to_pchan_num(struct arm_mhu *mhu, int irq)
85 {
86 	unsigned int pchan;
87 
88 	for (pchan = 0; pchan < MHU_CHANS; pchan++)
89 		if (mhu->mlink[pchan].irq == irq)
90 			break;
91 	return pchan;
92 }
93 
94 static struct mbox_chan *
mhu_db_mbox_irq_to_channel(struct arm_mhu * mhu,unsigned int pchan)95 mhu_db_mbox_irq_to_channel(struct arm_mhu *mhu, unsigned int pchan)
96 {
97 	unsigned long bits;
98 	unsigned int doorbell;
99 	struct mbox_chan *chan = NULL;
100 	struct mbox_controller *mbox = &mhu->mbox;
101 	void __iomem *base = mhu->mlink[pchan].rx_reg;
102 
103 	bits = readl_relaxed(base + INTR_STAT_OFS);
104 	if (!bits)
105 		/* No IRQs fired in specified physical channel */
106 		return NULL;
107 
108 	/* An IRQ has fired, find the associated channel */
109 	for (doorbell = 0; bits; doorbell++) {
110 		if (!test_and_clear_bit(doorbell, &bits))
111 			continue;
112 
113 		chan = mhu_db_mbox_to_channel(mbox, pchan, doorbell);
114 		if (chan)
115 			break;
116 		dev_err(mbox->dev,
117 			"Channel not registered: pchan: %d doorbell: %d\n",
118 			pchan, doorbell);
119 	}
120 
121 	return chan;
122 }
123 
mhu_db_mbox_rx_handler(int irq,void * data)124 static irqreturn_t mhu_db_mbox_rx_handler(int irq, void *data)
125 {
126 	struct mbox_chan *chan;
127 	struct arm_mhu *mhu = data;
128 	unsigned int pchan = mhu_db_mbox_irq_to_pchan_num(mhu, irq);
129 
130 	while (NULL != (chan = mhu_db_mbox_irq_to_channel(mhu, pchan))) {
131 		mbox_chan_received_data(chan, NULL);
132 		mhu_db_mbox_clear_irq(chan);
133 	}
134 
135 	return IRQ_HANDLED;
136 }
137 
mhu_db_last_tx_done(struct mbox_chan * chan)138 static bool mhu_db_last_tx_done(struct mbox_chan *chan)
139 {
140 	struct mhu_db_channel *chan_info = chan->con_priv;
141 	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
142 
143 	if (readl_relaxed(base + INTR_STAT_OFS) & BIT(chan_info->doorbell))
144 		return false;
145 
146 	return true;
147 }
148 
mhu_db_send_data(struct mbox_chan * chan,void * data)149 static int mhu_db_send_data(struct mbox_chan *chan, void *data)
150 {
151 	struct mhu_db_channel *chan_info = chan->con_priv;
152 	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
153 
154 	/* Send event to co-processor */
155 	writel_relaxed(BIT(chan_info->doorbell), base + INTR_SET_OFS);
156 
157 	return 0;
158 }
159 
mhu_db_startup(struct mbox_chan * chan)160 static int mhu_db_startup(struct mbox_chan *chan)
161 {
162 	mhu_db_mbox_clear_irq(chan);
163 	return 0;
164 }
165 
mhu_db_shutdown(struct mbox_chan * chan)166 static void mhu_db_shutdown(struct mbox_chan *chan)
167 {
168 	struct mhu_db_channel *chan_info = chan->con_priv;
169 	struct mbox_controller *mbox = &chan_info->mhu->mbox;
170 	int i;
171 
172 	for (i = 0; i < mbox->num_chans; i++)
173 		if (chan == &mbox->chans[i])
174 			break;
175 
176 	if (mbox->num_chans == i) {
177 		dev_warn(mbox->dev, "Request to free non-existent channel\n");
178 		return;
179 	}
180 
181 	/* Reset channel */
182 	mhu_db_mbox_clear_irq(chan);
183 	devm_kfree(mbox->dev, chan->con_priv);
184 	chan->con_priv = NULL;
185 }
186 
mhu_db_mbox_xlate(struct mbox_controller * mbox,const struct of_phandle_args * spec)187 static struct mbox_chan *mhu_db_mbox_xlate(struct mbox_controller *mbox,
188 					   const struct of_phandle_args *spec)
189 {
190 	struct arm_mhu *mhu = dev_get_drvdata(mbox->dev);
191 	struct mhu_db_channel *chan_info;
192 	struct mbox_chan *chan;
193 	unsigned int pchan = spec->args[0];
194 	unsigned int doorbell = spec->args[1];
195 	int i;
196 
197 	/* Bounds checking */
198 	if (pchan >= MHU_CHANS || doorbell >= MHU_NUM_DOORBELLS) {
199 		dev_err(mbox->dev,
200 			"Invalid channel requested pchan: %d doorbell: %d\n",
201 			pchan, doorbell);
202 		return ERR_PTR(-EINVAL);
203 	}
204 
205 	/* Is requested channel free? */
206 	chan = mhu_db_mbox_to_channel(mbox, pchan, doorbell);
207 	if (chan) {
208 		dev_err(mbox->dev, "Channel in use: pchan: %d doorbell: %d\n",
209 			pchan, doorbell);
210 		return ERR_PTR(-EBUSY);
211 	}
212 
213 	/* Find the first free slot */
214 	for (i = 0; i < mbox->num_chans; i++)
215 		if (!mbox->chans[i].con_priv)
216 			break;
217 
218 	if (mbox->num_chans == i) {
219 		dev_err(mbox->dev, "No free channels left\n");
220 		return ERR_PTR(-EBUSY);
221 	}
222 
223 	chan = &mbox->chans[i];
224 
225 	chan_info = devm_kzalloc(mbox->dev, sizeof(*chan_info), GFP_KERNEL);
226 	if (!chan_info)
227 		return ERR_PTR(-ENOMEM);
228 
229 	chan_info->mhu = mhu;
230 	chan_info->pchan = pchan;
231 	chan_info->doorbell = doorbell;
232 
233 	chan->con_priv = chan_info;
234 
235 	dev_dbg(mbox->dev, "mbox: created channel phys: %d doorbell: %d\n",
236 		pchan, doorbell);
237 
238 	return chan;
239 }
240 
241 static const struct mbox_chan_ops mhu_db_ops = {
242 	.send_data = mhu_db_send_data,
243 	.startup = mhu_db_startup,
244 	.shutdown = mhu_db_shutdown,
245 	.last_tx_done = mhu_db_last_tx_done,
246 };
247 
mhu_db_probe(struct amba_device * adev,const struct amba_id * id)248 static int mhu_db_probe(struct amba_device *adev, const struct amba_id *id)
249 {
250 	u32 cell_count;
251 	int i, err, max_chans;
252 	struct arm_mhu *mhu;
253 	struct mbox_chan *chans;
254 	struct device *dev = &adev->dev;
255 	struct device_node *np = dev->of_node;
256 	int mhu_reg[MHU_CHANS] = {
257 		MHU_LP_OFFSET, MHU_HP_OFFSET, MHU_SEC_OFFSET,
258 	};
259 
260 	if (!of_device_is_compatible(np, "arm,mhu-doorbell"))
261 		return -ENODEV;
262 
263 	err = of_property_read_u32(np, "#mbox-cells", &cell_count);
264 	if (err) {
265 		dev_err(dev, "failed to read #mbox-cells in '%pOF'\n", np);
266 		return err;
267 	}
268 
269 	if (cell_count == 2) {
270 		max_chans = MHU_CHAN_MAX;
271 	} else {
272 		dev_err(dev, "incorrect value of #mbox-cells in '%pOF'\n", np);
273 		return -EINVAL;
274 	}
275 
276 	mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);
277 	if (!mhu)
278 		return -ENOMEM;
279 
280 	mhu->base = devm_ioremap_resource(dev, &adev->res);
281 	if (IS_ERR(mhu->base))
282 		return PTR_ERR(mhu->base);
283 
284 	chans = devm_kcalloc(dev, max_chans, sizeof(*chans), GFP_KERNEL);
285 	if (!chans)
286 		return -ENOMEM;
287 
288 	mhu->dev = dev;
289 	mhu->mbox.dev = dev;
290 	mhu->mbox.chans = chans;
291 	mhu->mbox.num_chans = max_chans;
292 	mhu->mbox.txdone_irq = false;
293 	mhu->mbox.txdone_poll = true;
294 	mhu->mbox.txpoll_period = 1;
295 
296 	mhu->mbox.of_xlate = mhu_db_mbox_xlate;
297 	amba_set_drvdata(adev, mhu);
298 
299 	mhu->mbox.ops = &mhu_db_ops;
300 
301 	err = devm_mbox_controller_register(dev, &mhu->mbox);
302 	if (err) {
303 		dev_err(dev, "Failed to register mailboxes %d\n", err);
304 		return err;
305 	}
306 
307 	for (i = 0; i < MHU_CHANS; i++) {
308 		int irq = mhu->mlink[i].irq = adev->irq[i];
309 
310 		if (irq <= 0) {
311 			dev_dbg(dev, "No IRQ found for Channel %d\n", i);
312 			continue;
313 		}
314 
315 		mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];
316 		mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;
317 
318 		err = devm_request_threaded_irq(dev, irq, NULL,
319 						mhu_db_mbox_rx_handler,
320 						IRQF_ONESHOT, "mhu_db_link", mhu);
321 		if (err) {
322 			dev_err(dev, "Can't claim IRQ %d\n", irq);
323 			mbox_controller_unregister(&mhu->mbox);
324 			return err;
325 		}
326 	}
327 
328 	dev_info(dev, "ARM MHU Doorbell mailbox registered\n");
329 	return 0;
330 }
331 
332 static struct amba_id mhu_ids[] = {
333 	{
334 		.id	= 0x1bb098,
335 		.mask	= 0xffffff,
336 	},
337 	{ 0, 0 },
338 };
339 MODULE_DEVICE_TABLE(amba, mhu_ids);
340 
341 static struct amba_driver arm_mhu_db_driver = {
342 	.drv = {
343 		.name	= "mhu-doorbell",
344 	},
345 	.id_table	= mhu_ids,
346 	.probe		= mhu_db_probe,
347 };
348 module_amba_driver(arm_mhu_db_driver);
349 
350 MODULE_LICENSE("GPL v2");
351 MODULE_DESCRIPTION("ARM MHU Doorbell Driver");
352 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
353